Make sphinx.conf use the right python [bug 604402]

The issue we've had with Hudson in the past (the missing python26
executable in the virtualenv) seem to be resolved. I'm hopeful that
this will work this time, but there's a chance I'll back it out after
the next build.

configs/sphinx/sphinx.conf

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python26
 
 ID_FACTOR = 6